| 摘要 |
This amplifier circuit keeps low input impedance despite of variations of the transistor current amplification factor. An AM signal is amplified by the pre-amplifier(10) and the amplified signal is detected by the detection circuit(20). The detected signal is again amplified by the next stage amplifier(30) whose input impedance is used as a discharge path of the detection circuits. The amplifier(30) has coupled diode at each Darlington transistor between base and emitter to keep the variation of input impedance low.
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